for k in range(j-5,j): arr = reader[k, 0].values.tolist() arr = arr.append

It seems like there is a syntax error in the code snippet you provided.

Firstly, `arr = arr.append` should be `arr.append`. The `append()` function modifies the list in place and does not return anything, so there is no need to assign it back to `arr`.

Secondly, it looks like the code is missing a closing parenthesis. It should be:

for k in range(j-5,j):
    arr = reader[k, 0].values.tolist()
    arr.append(...)

Without knowing what `...` represents, it's hard to provide more specific help.